When the last remaining textparagraph is deleted, the resulting file will be corrupt.

@Test
  void removeLastRemainingTextParagraph() throws IOException {
    final XMLSlideShow ppt = new XMLSlideShow();

    final XSLFSlide slide = ppt.createSlide();

    final XSLFTextBox textBox = slide.createTextBox();
    textBox.setAnchor(new java.awt.Rectangle(0, 0, 100, 100));

    textBox.getTextParagraphs().get(0).getTextRuns().get(0).setText("lorem");
    textBox.addNewTextParagraph().addNewTextRun().setText("ipsum");

    assertEquals(2, textBox.getTextParagraphs().size());
    assertEquals("lorem\nipsum", textBox.getText());
    assertEquals("lorem", textBox.getTextParagraphs().get(0).getText());
    assertEquals("ipsum", textBox.getTextParagraphs().get(1).getText());

    textBox.removeTextParagraph(textBox.getTextParagraphs().get(1));

    assertEquals(1, textBox.getTextParagraphs().size());
    assertEquals("lorem", textBox.getText());
    assertEquals("lorem", textBox.getTextParagraphs().get(0).getText());

    String filepath = System.getProperty("java.io.tmpdir") + "valid_file.pptx";

    FileOutputStream fos = new FileOutputStream(filepath);
    ppt.write(fos);

    fos.close();

    System.out.println("file written to " + filepath);

    textBox.removeTextParagraph(textBox.getTextParagraphs().get(0));

    assertEquals(0, textBox.getTextParagraphs().size());
    assertEquals("", textBox.getText());

    filepath = System.getProperty("java.io.tmpdir") + "invalid_file.pptx";

    fos = new FileOutputStream(filepath);
    ppt.write(fos);

    fos.close();

    System.out.println("file written to " + filepath);
  }

It would be helpful if an exception was thrown explaining why the textparagraph cannot be deleted. This would ensure that a readable file would be produced and you would not have to debug and analyze to get to know the cause of the problem.



By the way, removing the last remaining textrun of a textparagraph does not result in a file corruption:

@Test
  void removeLastRemainingTextRun() throws IOException {
    final XMLSlideShow ppt = new XMLSlideShow();

    final XSLFSlide slide = ppt.createSlide();

    final XSLFTextBox textBox = slide.createTextBox();
    textBox.setAnchor(new java.awt.Rectangle(0, 0, 100, 100));

    textBox.getTextParagraphs().get(0).getTextRuns().get(0).setText("lorem");
    textBox.getTextParagraphs().get(0).addNewTextRun().setText("ipsum");

    assertEquals(1, textBox.getTextParagraphs().size());
    assertEquals(2, textBox.getTextParagraphs().get(0).getTextRuns().size());
    assertEquals("loremipsum", textBox.getText());
    assertEquals("lorem", textBox.getTextParagraphs().get(0).getTextRuns().get(0).getRawText());
    assertEquals("ipsum", textBox.getTextParagraphs().get(0).getTextRuns().get(1).getRawText());

    textBox.getTextParagraphs().get(0).removeTextRun(textBox.getTextParagraphs().get(0).getTextRuns().get(1));

    assertEquals(1, textBox.getTextParagraphs().size());
    assertEquals(1, textBox.getTextParagraphs().get(0).getTextRuns().size());
    assertEquals("lorem", textBox.getText());
    assertEquals("lorem", textBox.getTextParagraphs().get(0).getTextRuns().get(0).getRawText());

    String filepath = System.getProperty("java.io.tmpdir") + "valid_file.pptx";

    FileOutputStream fos = new FileOutputStream(filepath);
    ppt.write(fos);

    fos.close();

    System.out.println("file written to " + filepath);

    textBox.getTextParagraphs().get(0).removeTextRun(textBox.getTextParagraphs().get(0).getTextRuns().get(0));

    assertEquals(1, textBox.getTextParagraphs().size());
    assertEquals(0, textBox.getTextParagraphs().get(0).getTextRuns().size());
    assertEquals("", textBox.getText());

    filepath = System.getProperty("java.io.tmpdir") + "still_valid_file.pptx";

    fos = new FileOutputStream(filepath);
    ppt.write(fos);

    fos.close();

    System.out.println("file written to " + filepath);
  }